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11-01-16
SECTION 23 31 00HVAC DUCTS AND CASINGS
SPEC WRITER NOTES: 1. Use this section only for NCA projects.2. Delete between // // if not
applicable to project. Also delete any other item or paragraph not applicable in the section and renumber the paragraphs.
3. References to pressure in this section are gage pressure unless otherwise noted.
4. DESIGNER’S NOTE: Coordinate Specification with applicable standard equipment details and schedules: a. 23 31 00-01 Ductwork Square Vane Elbowsb. 23 31 00-02 Ductwork Radius Elbowsc. 23 31 00-03 Ductwork Transitions (with Equipment Mounted in Duct)d. 23 31 00-04 Supply Ductwork Take-Offse. 23 31 00-05 Supply Duct Takeoff-Air Terminal Unitsf. 23 31 00-06 Alternate Supply Duct Takeoff-Air Terminal Unitsg. 23 31 00-07 Exhaust or Return Branch Ductworkh. 23 31 00-08 Volume Damper Detaili. 23 31 00-09 Access Panel and Door Detailj. 23 31 00-10 Access Section Round Ductk. 23 31 00-11 Flexible Duct Connectionsl. 23 31 00-12 Section Thru Fire Damper Installationm. 23 31 00-14 Round Duct Hangersn. 23 31 00-24 Flexible Air Duct Connectoro. 23 31 00-26 Linear Slot Diffuser
5. NCA Master Specifications do not include information for fibrous glass ductwork, flat oval ductwork, or double wall ductwork. If project is to include any of these types of ductwork, the applicable information must be added to this section and any other applicable section.
PART 1 - GENERAL 1.1 DESCRIPTION
A. Ductwork and accessories for HVAC including supply air, return air,
outside air, exhaust, roof hoods, goosenecks, and relief systems.
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B. A complete listing of common acronyms and abbreviations are included in
Section 23 05 11, COMMON WORK RESULTS FOR HVAC.
C. Definitions:
1. SMACNA Standards as used in this specification means the HVAC Duct
Construction Standards, Metal and Flexible.
2. Seal or Sealing: Use of liquid or mastic sealant, with or without
compatible tape overlay, or gasketing of flanged joints, to keep air
leakage at duct joints, seams, and connections to an acceptable
minimum.
3. Duct Pressure Classification: SMACNA HVAC Duct Construction
Standards, Metal and Flexible.
4. Exposed Duct: Exposed to view in a finished room, //exposed to
weather//.
1.2 RELATED WORK SPEC WRITER NOTE: Retain one of two paragraphs below.
A. //Section 01 00 01, GENERAL REQUIREMENTS (Major NCA Projects).//
B. //Section 01 00 02, GENERAL REQUIREMENTS (Minor NCA Projects).//
C. Section 01 33 23, SHOP DRAWINGS, PRODUCT DATA, AND SAMPLES.
D. Section 01 42 19, REFERENCE STANDARDS.
E. Section 01 81 13, SUSTAINABLE DESIGN REQUIREMENTS.
F. //Section 01 91 00, GENERAL COMMISSIONING REQUIREMENTS.//
G. Section 07 84 00, FIRESTOPPING: Fire Stopping Material.
H. Section 08 90 00, LOUVERS AND VENTS: Outdoor and Exhaust Louvers.
SPEC WRITER NOTE: If Section 13 05 41 is included in this project the section shall be obtained from VA Masters.
I. //Section 13 05 41, SEISMIC RESTRAINT REQUIREMENTS FOR NON-STRUCTURAL
COMPONENTS: Seismic Reinforcing.//
J. Section 23 05 11, COMMON WORK RESULTS FOR HVAC: General mechanical
requirements and items which are common to more than one section of
Division 23.
K. Section 23 05 41, NOISE AND VIBRATION CONTROL FOR HVAC PIPING AND
EQUIPMENT: Noise Level Requirements.
L. Section 23 05 93, TESTING, ADJUSTING, AND BALANCING FOR HVAC: Testing
and Balancing of Air Flows.
M. Section 23 07 11, HVAC INSULATION: Duct Insulation
N. //Section 23 08 00, COMMISSIONING OF HVAC SYSTEMS.//
HVAC DUCTS AND CASINGS23 31 00 - 2
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O. //Section 23 09 23, DIRECT-DIGITAL CONTROL SYSTEM FOR HVAC: Duct Mounted
Instrumentation.//
P. Section 23 34 00, HVAC FANS: Return Air and Exhaust Air Fans.
Q. Section 23 36 00, AIR TERMINAL UNITS: Air Flow Control Valves and
Terminal Units.
R. Section 23 40 00, HVAC AIR CLEANING DEVICES: Air Filters and Filters'
Efficiencies.
S. Section 23 82 16, AIR COILS: Duct Mounted Coils.
T. Section 28 31 00, FIRE DETECTION AND ALARM: Smoke Detectors.
1.3 APPLICABLE PUBLICATIONS SPEC WRITER NOTE: Make material requirements agree with requirements specified in the referenced Applicable Publications. Verify and update the publication list to that which applies to the project, unless the reference applies to all mechanical systems. Publications that apply to all mechanical systems may not be specifically referenced in the body of the specification, but, shall form a part of this specification.
A. The publications listed below form a part of this specification to the
extent referenced. The publications are referenced in the text by the
basic designation only.
B. Air Movement and Control Association (AMCA):
512-2009................AMCA Listing Label Program
C. American Society of Civil Engineers (ASCE):
ASCE/SEI 7-2010.........Minimum Design Loads for Buildings and Other
Structures
D. American Society of Heating, Refrigerating and Air-Conditioning
Engineers, Inc. (ASHRAE):
62.1-2016...............Ventilation for Acceptable Indoor Air Quality
90.1-2013...............Energy Standard for Buildings Except Low-Rise
Residential Buildings
E. American Society for Testing and Materials (ASTM):
A653/A653M-2015e1.......Standard Specification for Steel Sheet, Zinc-
Coated (Galvanized) or Zinc-Iron Alloy-Coated
(Galvannealed) by the Hot-Dip Process
B209-2014...............Standard Specification for Aluminum and
Aluminum-Alloy Sheet and Plate
HVAC DUCTS AND CASINGS23 31 00 - 3
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C916-2014...............Standard Specification for Adhesives for Duct
Thermal Insulation
C1071-2012..............Standard Specification for Fibrous Glass Duct
Lining Insulation (Thermal and Sound Absorbing
Material)
E84-2015b...............Standard Test Method for Surface Burning
Characteristics of Building Materials
F. Environmental Protection Agency (EPA):
CFR 40, PART 59, Subpart D, EPA Method 24
G. National Fire Protection Association (NFPA):
90A-2015................Standard for the Installation of Air
Conditioning and Ventilating Systems
90B-2015................Standard for the Installation of Warm Air
Heating and Air-Conditioning Systems
96-2014.................Standard for Ventilation Control and Fire
Protection of Commercial Cooking Operations
H. North American Insulation Manufacturers Association (NAIMA):
AH124-2002..............Fibrous Glass Duct Liner Standard, 3rd Edition
I. Sheet Metal and Air Conditioning Contractors National Association
(SMACNA):
2005....................HVAC Duct Construction Standards, Metal and
Flexible, 3rd Edition
2012....................HVAC Air Duct Leakage Test Manual, 2nd Edition
2008....................IAQ Guidelines for Occupied Buildings Under
Construction, 2nd Edition
J. Underwriters Laboratories, Inc. (UL):
33-2010 (R2015).........Standard for Heat Responsive Links for Fire-
Protection Service
181-2013................Standard for Factory-Made Air Ducts and
Connectors
555-2006 (R2013)........Standard for Fire Dampers
555S-2014...............Standard for Smoke Dampers
1978-2010 (R2013).......Standard for Grease Ducts
1.4 SUBMITTALS A. Submittals, including number of required copies, shall be submitted in
accordance with Section 01 33 23, SHOP DRAWINGS, PRODUCT DATA, AND
SAMPLES.
HVAC DUCTS AND CASINGS23 31 00 - 4
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B. Information and material submitted under this section shall be marked
“SUBMITTED UNDER SECTION 23 31 00, DUCTS AND CASINGS”, with applicable
paragraph identification.
C. Manufacturer's Literature and Data including: Full item description and
optional features and accessories. Include dimensions, weights,
materials, applications, standard compliance, model numbers, size, and
capacity.
1. Rectangular ducts:
a. Schedules of duct systems, materials, and selected SMACNA
construction alternatives for joints, sealing, gage, and
reinforcement.
b. Duct liner.
c. Sealants and gaskets.
d. Access doors.
2. Round:
a. Manufacturer's details for duct fittings and joints.
b. Duct liner.
c. Sealants and gaskets.
d. Access sections.
e. Installation instructions.
3. Volume dampers, control dampers, and back draft dampers.
4. Hanger attachments.
5. Fire dampers, fire doors, and smoke dampers with installation
instructions.
6. Turning Vanes.
7. Sound attenuators, including pressure drop and acoustic performance.
8. Flexible ducts and clamps, with manufacturer's installation
instructions.
9. Flexible connections.
10. Instrument test fittings.
11. Details and design analysis of alternate or optional duct systems.
D. Coordination Drawings: Refer to paragraph, SUBMITTALS, in Section 23 05
11, COMMON WORK RESULTS FOR HVAC.
E. Complete operating and maintenance manuals including wiring diagrams,
technical data sheets, information for ordering replacement parts, and
troubleshooting guide:
1. Include complete list indicating all components of the systems.
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2. Include complete diagrams of the internal wiring for each item of
equipment.
3. Diagrams shall have their terminals identified to facilitate
installation, operation and maintenance.
F. //Completed System Readiness Checklist provided by the Commissioning
Agent and completed by the contractor, signed by a qualified technician
and dated on the date of completion, in accordance with the requirements
of Section 23 08 00, COMMISSIONING OF HVAC SYSTEMS.//
G. //Submit training plans and instructor qualifications in accordance with
the requirements of Section 23 08 00, COMMISSIONING OF HVAC SYSTEMS.//
1.5 QUALITY ASSURANCE A. Refer to paragraph, QUALITY ASSURANCE, in Section 23 05 11, COMMON WORK
RESULTS FOR HVAC.
B. Fire Safety Code: Comply with NFPA 90A.
C. Duct System Construction and Installation: Referenced SMACNA Standards
are the minimum acceptable quality.
D. Airstream Surfaces: Surfaces in contact with the airstream shall comply
with requirements in ASHRAE 62.1.
E. Duct Sealing, Air Leakage Criteria, and Air Leakage Tests: Ducts shall
be sealed as per duct sealing requirements of SMACNA Standards for duct
pressure classes shown on the drawings.
F. Duct accessories exposed to the air stream, such as dampers of all types
(except smoke dampers) and access openings, shall be of the same
material as the duct or provide at least the same level of corrosion
resistance.
G. ASHRAE Compliance: Applicable requirements in ASHRAE 90.1, Section 6.4.4
- "HVAC System Construction and Insulation."
H. Sealants and Adhesives: Comply with NFPA 90A and with ASTM C916.
1. For indoor applications, adhesive shall have a VOC content of 80 g/L
or less when calculated according to 40 CFR 59, Subpart D (EPA
Method 24).
1.6 AS-BUILT DOCUMENTATIONSPEC WRITER NOTE: Coordinate O&M Manual requirements with Section 01 00 01, GENERAL REQUIREMENTS (Major NCA Projects) or Section 01 00 02, GENERAL REQUIREMENTS (Minor NCA Projects). O&M manuals shall be submitted for content review as part of the close-out documents.
HVAC DUCTS AND CASINGS23 31 00 - 6
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A. Submit manufacturer’s literature and data updated to include submittal
review comments and any equipment substitutions.
B. Submit operation and maintenance data updated to include submittal
review comments, substitutions and construction revisions shall be //in
electronic version on CD or DVD// inserted into a three ring binder. All
aspects of system operation and maintenance procedures, including
applicable piping isometrics, wiring diagrams of all circuits, a written
description of system design, control logic, and sequence of operation
shall be included in the operation and maintenance manual. The
operations and maintenance manual shall include troubleshooting
techniques and procedures for emergency situations. Notes on all special
systems or devices shall be included. A List of recommended spare parts
(manufacturer, model number, and quantity) shall be furnished.
Information explaining any special knowledge or tools the owner will be
required to employ shall be inserted into the As-Built documentation.
C. The installing contractor shall maintain as-built drawings of each
completed phase for verification; and, shall provide the complete set at
the time of final systems certification testing. As-built drawings are
to be provided, and a copy of them in Auto-CAD version //____// provided
on CD or DVD. Should the installing contractor engage the testing
company to provide as-built or any portion thereof, it shall not be
deemed a conflict of interest or breach of the ‘third party testing
company’ requirement.
D. Certification documentation shall be provided to COR 10 working days
prior to submitting the request for final inspection. The documentation
shall include all test results, the names of individuals performing work
for the testing agency on this project, detailed procedures followed for
all tests, and certification that all results of tests were within
limits specified.
PART 2 - PRODUCTS 2.1 DUCT MATERIALS AND SEALANTS
A. General: Except for systems specified otherwise, construct ducts and
accessories of galvanized sheet steel, ASTM A653/A653M, coating G90; or,
aluminum sheet, ASTM B209, alloy 1100, 3003, or 5052.
B. Joint Sealing:
1. Sealant: Elastomeric compound, gun or brush grade, maximum 25 flame
spread and 50 smoke developed (dry state) compounded specifically for
sealing ductwork as recommended by the manufacturer. Generally
HVAC DUCTS AND CASINGS23 31 00 - 7
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provide liquid sealant, with or without compatible tape, for low
clearance slip joints and heavy, permanently elastic, mastic type
where clearances are larger. Oil base caulking and glazing compounds
are not acceptable because they do not retain elasticity and bond.
2. Tape: Use only tape specifically designated by the sealant
manufacturer and apply only over wet sealant. Pressure sensitive tape
shall not be used except as designated by sealant manufacturer.
3. Gaskets for Flanged Joints: Soft neoprene.
C. Approved factory made joints such as DUCTMATE SYSTEM may be used.
2.2 DUCT CONSTRUCTION AND INSTALLATION A. Follow SMACNA HVAC Duct Construction Standards.
SPEC WRITER NOTE: Verify that appropriate duct pressure classes as required by SAMCNA are shown on the drawings and in the paragraph below.
B. Duct Pressure Class: //500 Pa (2 inch WG)// //750 Pa (3 inch WG)//
//1000 Pa (4 inch WG)//.
C. Seal Class: As shown on the drawings and in accordance with SMACNA
Standards.
D. Round Ducts: Furnish duct and fittings made by the same manufacturer to
ensure good fit of joints. When submitted and approved in advance, round
ducting, with size converted on the basis of equal pressure drop may be
furnished in lieu of rectangular duct design shown on the drawings.
1. Elbows: Diameters 150 mm through 200 mm (6 through 8 inches) shall be
two sections die stamped; all others shall be gored construction,
maximum 18 degree angle, with all seams continuously welded or
standing seam. Coat galvanized areas of fittings damaged by welding
with corrosion resistant aluminum paint or galvanized repair
compound.
2. Provide bell mouth, conical tees or taps, laterals, reducers, and
other low loss fittings as shown in SMACNA HVAC Duct Construction
Standards.
E. Volume Dampers: Single blade, opposed blade, or multi-blade type as
detailed in SMACNA Standards.
F. Duct Hangers and Supports: Refer to SMACNA Standards. Do not use trapeze
hangers for round duct.
SPEC WRITER NOTE: For Outside air ducts, duct liner is prohibited. Provide exterior insulation only.
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2.3 DUCT LINER (WHERE INDICATED ON DRAWINGS) A. Duct sizes shown on drawings for lined duct are clear opening inside
lining.
B. Rectangular Duct Liner: ASTM C1071, Type I (flexible), or Type II
(board), 25 mm (one inch) minimum thickness, applied with mechanical
fasteners and 100 percent coverage of adhesive in conformance with
SMACNA HVAC Duct Construction Standards.
2.4 DUCT ACCESS DOORS, PANELS AND SECTIONS A. Install access doors with swing against duct static pressure.
B. Provide access doors, sized and located for maintenance work, in the
following locations:
1. Upstream and downstream of each duct mounted coil.
2. Each fire damper (for link service), smoke damper, and automatic
control damper.
3. Each duct mounted smoke detector.
4. Downstream from manual volume dampers, control dampers, backdraft
dampers, and equipment.
5. Upstream //and downstream// from turning vanes.
6. Upstream or downstream from duct silencers.
7. Control devices requiring inspection.
C. Duct-Mounted Access Doors: Fabricate access panels according to SMACNA's
"HVAC Duct Construction Standards - Metal and Flexible"; Figures 7-2 (7-
2M), "Duct Access Doors and Panels," and 7-3, "Access Doors - Round
Duct."
1. Door:
a. Double wall, rectangular.
b. Galvanized sheet metal with insulation fill and thickness as
indicated for duct pressure class.
c. Hinges and Latches: 25 by 25 mm (1 by 1 inch) butt or piano hinge
and cam latches.
d. Fabricate doors airtight and suitable for duct pressure class.
2. Frame: Galvanized sheet steel, with bend-over tabs and foam gaskets.
3. Number of Hinges and Locks:
a. Access Doors Less Than 300 mm (12 inches) Square: No hinges and
two sash locks.
b. Access Doors up to //450 mm (18 inches)// Square: //Two
hinges// //Continuous// and two sash locks.
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c. Access Doors up to 600 by 1200 mm (24 by 48 inches): //Three
hinges// //Continuous// and two compression latches// with outside
and inside handles//.
D. Access Doors Greater Than 600 by 1200 mm (24 by 48 inches): //Four
hinges// //Continuous// and two compression latches with outside and
inside handles, labeled according to UL 1978 by an NRTL.
E. Panel and Frame: Minimum thickness //1.3 mm (0.05 inch) carbon// //1.1
mm (0.045 inch) stainless// steel.
F. Fasteners: //Carbon// //Stainless// steel. Panel fasteners shall not
penetrate duct wall.
G. Gasket: Comply with NFPA 96; grease-tight, high-temperature ceramic
fiber, rated for minimum 1093 degrees C (2000 degrees F).
H. Minimum Pressure Rating: 2500 Pa (10 inch WG), positive or negative.
I. Openings shall be as large as feasible in small ducts, 300 mm by 300 mm
(12 inch by 12 inch) minimum where possible. Access sections in
insulated ducts shall be double-wall, insulated.
1. Refer to SMACNA HVAC Duct Construction Standards.
2.5 FIRE DAMPERS A. Type: Static and dynamic; rated and labeled according to UL 555 by an
NRTL.
B. Closing rating in ducts up to 1 kPa (4 inch WG) static pressure class
and minimum 10 m/s (2000 fpm) velocity
C. Mounting Orientation: Vertical or horizontal as indicated.
D. Galvanized steel, interlocking blade type, UL listing and
label, //1-1/2// //3// hour rating, 74 degrees C (165 degrees F) fusible
link, 100 percent free opening with no part of the blade stack or damper
frame in the air stream.
E. Fire dampers shall be galvanized steel.
1. The damper frame may be of design and length as to function as the
mounting sleeve, thus eliminating the need for a separate sleeve, as
allowed by UL 555. Otherwise provide sleeves and mounting angles,
minimum 1.9 mm (14 gage), required to provide installation equivalent
to the damper manufacturer's UL test installation.
2. Submit manufacturer's installation instructions conforming to UL 555
rating test.
2.6 SMOKE DAMPERSA. Maximum air velocity through free area of open damper: 450 m/min (1500
fpm).
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B. Maximum static pressure loss at maximum velocity: 32 Pa (0.13 inch WG).
C. Leakage: Class I.
D. Minimum requirements for dampers:
1. Shall comply with requirements of UL 555S, except for the Fire
Endurance and Hose Stream Test.
2. Frame: Galvanized steel channel with side, top, and bottom stops or
seals.
3. Blades: Galvanized steel, parallel type preferably, 300 mm (12 inch)
maximum width, edges sealed with neoprene, rubber, or felt if
required to meet minimum leakage. Airfoil (streamlined) type for
minimum noise generation and pressure drop are preferred for duct
mounted dampers.
4. Shafts: Galvanized steel.
5. Bearings: Nylon, bronze sleeve or ball type.
6. Hardware: Zinc plated.
7. Smoke Detector: Integral, factory wired for single-point connection.
8. Operation: Automatic open/close. Modulating or two-position action as
indicated on the drawings. No smoke damper that requires manual reset
or link replacement after actuation is acceptable. See drawings for
required control operation.
9. Auxiliary switches for //signaling// //fan control// //or//
//position indication// as indicated in the drawings.
E. Motor operator (actuator): Provide electric as required by the automatic
control system, externally mounted on stand-offs to allow complete
insulation coverage.
2.7 BACKDRAFT AND PRESSURE RELIEF DAMPERSA. Description: Gravity balanced.
B. Maximum Air Velocity: //5.1 m/s (1000 fpm)// //6.4 m/s (1250 fpm)// //10
m/s (2000 fpm)// //15 m/s (3000 fpm)// // //.
C. Maximum System Pressure: //0.25 kPa (1 inch WG)// //0.5 kPa (2 inch
WG)// //0.8 kPa (3 inch WG)// //1.5 kPa (6 inch WG)// // //.
D. Frame: Hat-shaped, //1.3 mm (0.05 inch) thick, galvanized sheet
steel// //2.4 mm (0.094 inch) thick, galvanized sheet steel// //1.6 mm
(0.063 inch) thick extruded aluminum// //0.8 mm (0.03 inch) thick
stainless steel// //1.3 mm (0.05 inch) thick stainless steel//, with
welded corners or mechanically attached// and mounting flange//.
E. Blades: Multiple single-piece blades, //center pivoted,// //off-center
pivoted,// //end pivoted,// maximum 150 mm (6 inch) width, //0.6 mm
HVAC DUCTS AND CASINGS23 31 00 - 11
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(0.025 inch) thick, roll-formed aluminum// //1.2 mm (0.047 inch) thick
aluminum sheet// //noncombustible, tear-resistant, neoprene-coated
fiberglass// with sealed edges.
F. Blade Action: Parallel.
G. Blade Seals: //Felt// //Vinyl foam// //Extruded vinyl, mechanically
locked// //Neoprene, mechanically locked//.
H. Blade Axles:
1. Material: //Nonferrous metal// //Galvanized steel// //Plated
steel// //Stainless steel// //Nonmetallic// //Aluminum//.
2. Diameter: //5 mm (3/160 inch)// // //.
I. Tie Bars and Brackets: //Aluminum// //Galvanized steel//.
J. Return Spring: Adjustable tension.
K. Bearings: //Steel ball// //or// //synthetic pivot bushings//.
L. Accessories:
1. Adjustment device to permit setting for varying differential static
pressure.
2. Counterweights and spring-assist kits for vertical airflow
installations.
3. Electric actuators.
4. Chain pulls.
5. Screen Mounting: Front mounted in sleeve.
a. Sleeve Thickness: 1.0 mm (20 gage) minimum.
b. Sleeve Length: 150 mm (6 inches) minimum.
6. Screen Mounting: Rear mounted.
7. Screen Material: //Galvanized steel// //Aluminum//.
8. Screen Type: //Bird// //Insect//.
9. 90 degree stops.
2.8 BAROMETRIC RELIEF DAMPERSA. Suitable for horizontal or vertical mounting.
B. Maximum Air Velocity: //5.1 m/s (1000 fpm)// //6.4 m/s (1250 fpm)// //10
m/s (2000 fpm)// //13 m/s (2500 fpm)// // //.
C. Maximum System Pressure: //0.5 kPa (2 inch WG)// //0.8 kPa (3 inch WG)//
//1.5 kPa (6 inch WG)// //2.5 kPa (10 inch WG)// // //.
D. Frame: Hat-shaped, //1.3 mm (0.05 inch) thick, galvanized sheet
steel// //2.4 mm (0.094 inch) thick, galvanized sheet steel// //1.6 mm
(0.063 inch) thick extruded aluminum// //0.8 mm (0.03 inch) thick
stainless steel// //1.3 mm (0.05 inch) thick stainless steel//, with
welded corners or mechanically attached// and mounting flange//.
HVAC DUCTS AND CASINGS23 31 00 - 12
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E. Blades:
1. Multiple, //0.6 mm (0.025 inch) thick, roll-formed aluminum// //1.2
mm (0.047 inch) thick aluminum sheet//.
2. Maximum Width: 150 mm (6 inches).
3. Action: Parallel.
4. Balance: Gravity.
5. //Eccentrically pivoted// //Off-center pivoted// //End pivoted//.
F. Blade Seals: //Vinyl// //Neoprene//.
G. Blade Axles: //Galvanized steel// //Nonferrous metal// //Plated
steel// //Stainless steel// //Nonmetallic//.
H. Tie Bars and Brackets:
1. Material: //Aluminum// //Galvanized steel//.
2. Rattle free with 90 degree stop.
I. Return Spring: Adjustable tension.
J. Bearings: //Synthetic// //Stainless steel// //Bronze//.
K. Accessories:
1. Flange on intake.
2. Adjustment device to permit setting for varying differential static
pressures.
3. // //.
2.9 MANUAL VOLUME DAMPERSA. Standard, Steel, Manual Volume Dampers:
1. Standard leakage rating, with linkage outside airstream.
2. Suitable for horizontal or vertical applications.
3. Frames:
a. Frame: Hat-shaped, //2.4 mm (3/32 inch) thick, galvanized sheet
steel// //1.3 mm (0.05 inch) thick stainless steel//.
b. Mitered and welded corners.
c. Flanges for attaching to walls and flangeless frames for
installing in ducts.
4. Blades:
a. Multiple or single blade.
b. Parallel- or opposed-blade design.
c. Stiffen damper blades for stability.
d. //Galvanized// //Stainless//-steel, 1.62 mm (0.064 inch) thick.
5. Blade Axles: //Galvanized steel// //Stainless steel// //Nonferrous
metal//.
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6. Bearings:
a. //Oil-impregnated bronze// //Molded synthetic// //Oil-impregnated
stainless-steel sleeve// //Stainless-steel sleeve//.
b. Dampers in ducts with pressure classes of 750 Pa (3 inch WG) or
less shall have axles full length of damper blades and bearings at
both ends of operating shaft.
7. Tie Bars and Brackets: Galvanized steel.
B. Standard, Aluminum, Manual Volume Dampers:
1. Standard leakage rating, with linkage outside airstream.
2. Suitable for horizontal or vertical applications.
3. Frames: Hat-shaped, 2.5 mm (0.10 inch) thick, aluminum sheet
channels; frames with flanges for attaching to walls and flangeless
frames for installing in ducts.
4. Blades:
a. Multiple or single blade.
b. Parallel- or opposed-blade design.
c. Stiffen damper blades for stability.
d. Roll-Formed Aluminum Blades: 2.5 mm (0.10 inch) thick aluminum
sheet.
e. Extruded-Aluminum Blades: 1.3 mm (0.050 inch) thick extruded
aluminum.
5. Blade Axles: //Galvanized steel// //Stainless steel// //Nonferrous
metal//.
6. Bearings:
a. //Oil-impregnated bronze// //Molded synthetic// //Stainless-steel
sleeve//.
b. Dampers in ducts with pressure classes of 750 Pa (3 inch WG) or
less shall have axles full length of damper blades and bearings at
both ends of operating shaft.
7. Tie Bars and Brackets: Aluminum.
2.10 CONTROL DAMPERSA. Low-leakage rating, with linkage outside airstream, and bearing AMCA's
Certified Ratings Seal for both air performance and air leakage.
B. Frames:
1. //Hat// //U// //Angle// shaped.
2. //2.4 mm (0.094 inch) thick, galvanized sheet steel// //1.3 mm (0.05
inch) thick stainless steel//.
3. //Mitered and welded// //Interlocking, gusseted// corners.
HVAC DUCTS AND CASINGS23 31 00 - 14
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C. Blades:
1. Multiple blade with maximum blade width of //150 mm (6 inches)//
//200 mm (8 inches)//.
2. //Parallel// //Parallel- and opposed// //Opposed//-blade design.
3. Galvanized-steel// //Stainless steel// //Aluminum//.
4. //1.62 mm (0.064 inch) thick single skin// //1.9 mm (0.0747 inch)
thick dual skin//.
5. Blade Edging: //Closed-cell neoprene// //PVC//.
6. Blade Edging: Inflatable seal blade edging, or replaceable rubber
seals.
D. Blade Axles: 15 mm (1/2 inch) diameter; //galvanized steel// //stainless
steel// //nonferrous metal//; blade-linkage hardware of zinc-plated
steel and brass; ends sealed against blade bearings.
1. Operating Temperature Range: From minus 40 to plus 93 degrees C
(minus 40 to plus 200 degrees F).
E. Bearings:
1. //Oil-impregnated bronze// //Molded synthetic// //Oil-impregnated
stainless-steel sleeve// //Stainless-steel sleeve//.
2. Dampers in ducts with pressure classes of 750 Pa (3 inch WG) or less
shall have axles full length of damper blades and bearings at both
ends of operating shaft.
3. Thrust bearings at each end of every blade.
2.11 FLEXIBLE AIR DUCT A. General: Factory fabricated, complying with NFPA 90A for connectors not
passing through floors or buildings. Flexible ducts shall not penetrate
any fire or smoke barrier which is required to have a fire resistance
rating of one hour or more. Flexible duct length shall not exceed 1.5 m
(5 feet). Provide insulated flexible air duct connectors in supply air
duct systems and elsewhere as shown.
B. Flexible ducts shall be listed by Underwriters Laboratories, Inc.,
complying with UL 181. Ducts greater than 200 mm (8 inches) in diameter
shall be Class 1. Ducts 200 mm (8 inches) in diameter and smaller may be
Class 1 or Class 2.
C. Insulated Flexible Air Duct: Factory made including mineral fiber
insulation with maximum C factor of 0.25 at 24 degrees C (75 degrees F)
mean temperature, encased with a low permeability moisture barrier outer
jacket, having a puncture resistance of not less than 50 Beach Units.
Acoustic insertion loss shall not be less than 3 dB per 300 mm (1 foot)
HVAC DUCTS AND CASINGS23 31 00 - 15
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of straight duct, at 500 Hz, based on 150 mm (6 inch) duct, of 750 m/min
(2500 fpm).
D. Application Criteria:
1. Temperature range: minus 18 to 93 degrees C (0 to 200 degrees F)
internal.
2. Maximum working velocity: 1200 m/min (4000 fpm).
3. Minimum working pressure: 2500 Pa (10 inch WG) positive, 500 Pa (2
inch WG) negative.
E. Duct Clamps: 100 percent nylon strap, 80 kg (175 pounds) minimum loop
tensile strength manufactured for this purpose or stainless steel strap
with cadmium plated worm gear tightening device. Apply clamps with
sealant and as approved for UL 181, Class 1 installation.
2.12 FLEXIBLE CONNECTIONS A. Where duct connections are made to fans and air handling units, install
a non-combustible flexible connection of 822 g (29 ounce) neoprene
coated fiberglass fabric, approximately 150 mm (6 inches) wide.
B. Coatings and Adhesives: Comply with UL 181, Class 1. For connections
exposed to sun and weather provide hypalon coating in lieu of neoprene.
Burning characteristics shall conform to NFPA 90A.
1. Tensile Strength: 84 N/mm (480 lbf/inch) in the warp and 63 N/mm (360
lbf/inch) in the filling.
2. Service Temperature: Minus 40 to plus 93 degrees C (Minus 40 to plus
200 degrees F)
C. Securely fasten flexible connections to round ducts with stainless steel
or zinc-coated iron draw bands with worm gear fastener. For rectangular
connections, crimp fabric to sheet metal and fasten sheet metal to ducts
by screws 50 mm (2 inches) on center. Fabric shall not be stressed other
than by air pressure. Allow at least 25 mm (one inch) slack to ensure
that no vibration is transmitted.
2.13 TURNING VANESA. Manufactured Turning Vanes for Metal Ducts: Curved blades of galvanized
sheet steel; support with bars perpendicular to blades set; set into
vane runners suitable for duct mounting.
B. General Requirements: Comply with SMACNA's "HVAC Duct Construction
Standards - Metal and Flexible"; Figures 4-3, "Vanes and Vane Runners,"
and 4-4, "Vane Support in Elbows."
C. Vane Construction: //Single// //Double// wall.
HVAC DUCTS AND CASINGS23 31 00 - 16
11-01-16
D. Vane Construction: Single wall for ducts up to //1200 mm (48
inches)// // // wide and double wall for larger dimensions.
2.14 SOUND ATTENUATING UNITS A. Casing, not less than 1.0 mm (20 gage) galvanized sheet steel, or 1.3 mm
(18 gage) aluminum fitted with suitable flanges to make clean airtight
connections to ductwork. Sound-absorbent material faced with glass fiber
cloth and covered with not less than 0.6 mm (24 gage) or heavier
galvanized perforated sheet steel, or 0.85 mm (22 gage) or heavier
perforated aluminum. Perforations shall not exceed 4 mm (5/32 inch)
diameter, approximately 25 percent free area. Sound absorbent material
shall be long glass fiber acoustic blanket meeting requirements of NFPA
90A.
B. Entire unit shall be completely air tight and free of vibration and
buckling at internal static pressures up to 2000 Pa (8 inch WG) at
operating velocities.
C. Pressure drop through each unit: Not to exceed indicated value at design
air quantities indicated.
D. Submit complete independent laboratory test data showing pressure drop
and acoustical performance.
E. Cap open ends of attenuators at factory with plastic, heavy duty paper,
cardboard, or other appropriate material to prevent entrance of dirt,
water, or any other foreign matter to inside of attenuator. Caps shall
not be removed until attenuator is installed in duct system.
2.15 PREFABRICATED ROOF CURBS A. Galvanized steel or extruded aluminum //300 mm (12 inches)// //450 mm
(18 inches)// //600 mm (24 inches)// above finish roof service,
continuous welded corner seams, treated wood nailer, 40 mm (1-1/2 inch)
thick, 48 kg/cubic meter (3 pound/cubic feet) density rigid mineral
fiberboard insulation with metal liner, built-in cant strip (except for
gypsum or tectum decks). For surface insulated roof deck, provide raised
cant strip (recessed mounting flange) to start at the upper surface of
the insulation. Curbs shall be constructed for pitched roof or ridge
mounting as required to keep top of curb level.
2.16 FIRESTOPPING MATERIALA. Refer to Section 07 84 00, FIRESTOPPING.
2.17 //SEISMIC RESTRAINT FOR DUCTWORKA. Refer to Section 13 05 41, SEISMIC RESTRAINT REQUIREMENTS FOR NON-
STRUCTURAL COMPONENTS.//
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2.18 THERMOMETER (AIR) A. Refer to Section 23 09 23, DIRECT-DIGITAL CONTROL SYSTEM FOR HVAC.
2.19 INSTRUMENT TEST FITTINGS A. Manufactured type with a minimum 50 mm (2 inch) length for insulated
duct, and a minimum 25 mm (1 inch) length for duct not insulated. Test
hole shall have a flat gasket for rectangular ducts and a concave gasket
for round ducts at the base, and a screw cap to prevent air leakage.
B. Provide instrument test holes at each duct mounted temperature sensor or
transmitter, and at entering and leaving side of each heating coil,
cooling coil, and heat recovery unit.
2.20 ROOF HOODS AND GOOSENECKSA. Factory or shop fabricate according to SMACNA's "HVAC Duct Construction
Standards - Metal and Flexible," Figures 6-5 and 6-6.
B. Materials: Galvanized-steel sheet, minimum 1.62 mm (0.064 inch) thick
base and 1.0 mm (0.040 inch) thick hood. //Aluminum sheet, minimum 1.6
mm (0.063 inch) thick base and 1.27 mm (0.050 inch) thick hood; suitably
reinforced.//
C. Roof Curb: Galvanized steel or extruded aluminum //300 mm (12
inches)// //450 mm (18 inches)// //600 mm (24 inches)// above finish
roof service, continuous welded corner seams, treated wood nailer, 40 mm
(1-1/2 inch) thick, 48 kg/cubic meter (3 pound/cubic feet) density rigid
mineral fiberboard insulation with metal liner, built-in cant strip
(except for gypsum or tectum decks). For surface insulated roof deck,
provide raised cant strip (recessed mounting flange) to start at the
upper surface of the insulation. Curbs shall be constructed for pitched
roof or ridge mounting as required to keep top of curb level.
D. Bird Screening: Flattened, expanded aluminum, 20 mm by 1.27 mm (3/4 inch
by 0.050 inch) thick.
E. Insect Screens - Aluminum or Stainless Steel:
1. Exhaust to openings: not less than 6 mm (1/4 inch) and not greater
than 15 mm (1/2 inch).
2. Intake openings: greater than 6 mm (1/4 inch) and not greater than 25
mm (1 inch).
F. Galvanized-Steel Sheet Finish:
1. Surface Preparation: Clean surfaces of dirt, grease, and other
contaminants. Clean welds, mechanical connections, and abraded areas.
2. Field-Painted Finish: Apply an air-dried primer immediately after
cleaning.
HVAC DUCTS AND CASINGS23 31 00 - 18
11-01-16
PART 3 - EXECURTION3.1 INSTALLATION
A. If an installation is unsatisfactory to the COR, the Contractor shall
correct the installation at no additional cost or time to the
Government.
B. Comply with provisions of Section 23 05 11, COMMON WORK RESULTS FOR
HVAC, particularly regarding coordination with other trades and work in
existing buildings.
C. Install duct accessories of materials suited to duct materials; use
galvanized-steel accessories in galvanized-steel and aluminum
accessories in aluminum ducts.
D. Install //backdraft// //control// dampers at inlet of exhaust fans or
exhaust ducts as close as possible to exhaust fan, unless otherwise
indicated.
E. Install volume dampers at points on supply, return, and exhaust systems
where branches extend from larger ducts. Where dampers are installed in
ducts having duct liner, install dampers with hat channels of same depth
as liner and terminate liner with nosing at hat channel.
1. Install steel volume dampers in steel ducts.
2. Install aluminum volume dampers in aluminum ducts.
F. Access Door Sizes:
1. One-Hand or Inspection Access: 200 mm by 125 mm (8 inches by 5
inches).
2. Two-Hand Access: 300 mm by 150 mm (12 inches by 6 inches).
3. Head and Hand Access: 450 mm by 250 mm (18 inches by 10 inches).
4. Head and Shoulders Access: 533 mm by 356 mm (21 inches by 14 inches).
5. Body Access: 635 mm by 356 mm (25 inches by 14 inches).
6. Body plus Ladder Access: 635 mm by 432 mm (25 inches by 17 inches).
G. Label access doors according to Section 230553 "Identification for HVAC
Piping and Equipment" to indicate the purpose of access door.
H. Install ducts with fewest possible joints.
I. Install factory- or shop-fabricated fittings for changes in direction,
size, shape, and for branch connections.
J. Unless otherwise indicated, install ducts vertically and horizontally,
and parallel and perpendicular to building lines.
K. Install ducts close to walls, overhead construction, columns, and other
structural and permanent enclosure elements of building.
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11-01-16
L. Install ducts with a clearance of 25 mm (1 inch), plus allowance for
insulation thickness.
M. Route ducts to avoid passing through transformer vaults and electrical
equipment rooms and enclosures.
N. Where ducts pass through non-fire-rated interior partitions and exterior
walls and are exposed to view, cover the opening between the partition
and duct or duct insulation with sheet metal flanges of same metal
thickness as the duct. Overlap openings on four sides by at least 40 mm
(1-1/2 inches).
O. Protect duct interiors from moisture, construction debris and dust, and
other foreign materials.// Comply with SMACNA IAQ Guidelines for
Occupied Buildings Under Construction, Appendix G, "Duct Cleanliness for
New Construction Guidelines."//
P. Fabricate and install ductwork and accessories in accordance with
referenced SMACNA Standards:
1. Drawings show the general layout of ductwork and accessories but do
not show all required fittings and offsets that may be necessary to
connect ducts to equipment, boxes, diffusers, grilles, etc., and to
coordinate with other trades. Fabricate ductwork based on field
measurements. Provide all necessary fittings and offsets at no
additional cost to the government. Coordinate with other trades for
space available and relative location of HVAC equipment and
accessories on ceiling grid. Duct sizes on the drawings are inside
dimensions which shall be altered by Contractor to other dimensions
with the same air handling characteristics where necessary to avoid
interferences and clearance difficulties.
2. Provide duct transitions, offsets and connections to dampers, coils,
and other equipment in accordance with SMACNA HVAC Duct Construction
Standards. Provide streamliner when an obstruction cannot be avoided
and must be taken in by a duct. Repair galvanized areas with
galvanizing repair compound.
3. Provide bolted construction and tie-rod reinforcement in accordance
with SMACNA HVAC Duct Construction Standards.
Q. Install duct hangers and supports in accordance with SMACNA HVAC Duct
Construction Standards.
R. Install fire dampers and smoke dampers in accordance with the
manufacturer's instructions to conform to the installation used for the
rating test.
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11-01-16
S. Seal openings around duct penetrations of floors and fire rated
partitions with fire stop material as required by NFPA 90A.
T. Flexible duct installation: Refer to SMACNA HVAC Duct Construction
Standards. Ducts shall be continuous, single pieces not over 1.5 m (5
feet) long, as straight and short as feasible, adequately supported.
Centerline radius of bends shall be not less than 2 duct diameters. Make
connections with clamps as recommended by SMACNA Standards. Clamp per
SMACNA Standards with one clamp on the core duct and one on the
insulation jacket. Flexible ducts shall not penetrate floors, or any
chase or partition designated as a fire or smoke barrier, including
corridor partitions fire rated 1-hour or 2-hour. Support flexible ducts
per SMACNA HVAC Duct Construction Standards.
U. Control Damper Installation:
1. Provide necessary blank-off plates required to install dampers that
are smaller than duct size. Provide necessary transitions required to
install dampers larger than duct size.
2. Install all damper control/adjustment devices on stand-offs to allow
complete coverage of insulation.
V. //Air Flow Measuring Devices (AFMD): Install units with minimum straight
run distances, upstream and downstream as recommended by the
manufacturer.//
W. Low Pressure Duct Liner: Install in accordance with SMACNA HVAC Duct
Construction Standards.
X. Protection and Cleaning: Adequately protect equipment and materials
against physical damage. Place equipment in first-class operating
condition, or return to source of supply for repair or replacement, as
determined by COR. Protect equipment and ducts during construction
against entry of foreign matter to the inside and clean both inside and
outside before operation and painting. When new ducts are connected to
existing ductwork, clean both new and existing ductwork by mopping and
vacuum cleaning inside and outside before operation.
3.2 DUCT LEAKAGE TESTS AND REPAIR A. Leak testing company shall be independent of the sheet metal company
employed by General Contractor.
B. //Ductwork leak test shall be performed for the entire air distribution
supply, return, exhaust system section-by-section including fans, coils,
and filter section designated as static pressure class 750 Pa (3 inch
WG) and above. All supply ductwork less than 500 Pa (2 inch WG) shall
HVAC DUCTS AND CASINGS23 31 00 - 21
11-01-16
also be tested where there is no air terminal unit employed in the
system.//
C. Test procedure, apparatus, and report shall conform to SMACNA HVAC Air
Duct Leakage Test Manual. The maximum leakage rate allowed is 4 percent
of the design air flow rate.
SPEC WRITE NOTES: SMACNA requires the system designer to show pressure classes for establishing leakage test requirements for duct systems. Refer to SMACNA HVAC Duct Construction Standards for pressure classes, associated operating pressure ranges and for seals and normal leakage classification. Verify pressure classes are shown on the drawings.
D. All ductwork shall be leak tested first before enclosed in a shaft or
covered in other inaccessible areas.
E. All tests shall be performed in the presence of the COR and the Test and
Balance agency. The Test and Balance agency shall measure and record
duct leakage and report to the COR and identify leakage source with
excessive leakage.
F. If any portion of the duct system tested fails to meet the permissible
leakage level, rectify sealing of ductwork to bring it into compliance
and retest until acceptable leakage is demonstrated to the COR.
G. All tests and necessary repairs shall be completed prior to insulation
or concealment of ductwork.
H. Make sure all openings used for testing flow and temperatures by TAB
contractor are sealed properly.
SPEC WRITER NOTE:Specify wind velocity as per ASCE/SEI 7 where wind velocity exceeds 90 mph in coastal areas.
3.3 //DUCTWORK EXPOSED TO WIND VELOCITY A. Provide additional support and bracing to all exposed ductwork installed
on the roof or outside the building to withstand wind velocity
of // // km/h (// // mph). //
3.4 TESTING, ADJUSTING, AND BALANCING (TAB)A. Refer to Section 23 05 93, TESTING, ADJUSTING, AND BALANCING FOR HVAC.
3.5 STARTUP AND TESTINGA. Make tests as recommended by product manufacturer and listed standards
and under actual or simulated operating conditions and prove full
compliance with design and specified requirements. Tests of the various
HVAC DUCTS AND CASINGS23 31 00 - 22
11-01-16
items of equipment shall be performed simultaneously with the system of
which each item is an integral part.
B. When any defects are detected, correct defects and repeat test at no
additional cost or time to the Government.
C. //The Commissioning Agent will observe startup and contractor testing of
selected equipment. Coordinate the startup and contractor testing
schedules with the COR and Commissioning Agent. Provide a minimum notice
of 10 working days prior to startup and testing.//
3.6 //COMMISSIONINGA. Provide commissioning documentation in accordance with the requirements
of Section 23 08 00, COMMISSIONING OF HVAC SYSTEMS.
B. Components provided under this section of the specification will be
tested as part of a larger system.//
3.7 DEMONSTRATION AND TRAININGA. Provide services of manufacturer’s technical representative for //four//
// // hour//s// to instruct each VA personnel responsible in the
operation and maintenance of units.
B. //Submit training plans and instructor qualifications in accordance with
the requirements of Section 23 08 00, COMMISSIONING OF HVAC SYSTEMS.//
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